This disclosure relates generally to systems for harvesting energy from downhole fluid flow based on Vortex Induced Vibration (VIV).
Fiber optic distributed sensing systems were developed in the 1980s to replace older measurement systems composed of multiple individual sensors.
Fiber optic distributed sensing systems are commonly based on Optical Time-Domain Reflectometry (OTDR) and utilizes techniques originally derived from telecommunications cable testing. Today fiber optic distributed sensing systems provides a cost-effective way of obtaining hundreds, or even thousands, of highly accurate, high-resolution measurements and today find widespread acceptance in industries such as oil and gas, electrical power, and process control.
Energy harvesting is the process by which energy readily available from the environment is captured and converted into usable electrical energy. Historically, downhole electrical power has been either via electrical wiring from the surface, limited life batteries, or turbines powered by drilling mud for MWD. All of these methods were used for creating significant power downhole. The advent of nano powered sensors, ultralow power microprocessors and other minimal powered devices opens up a new era for downhole telemetry when combined with fiber optic data transmission.
FIG. 3 shows a conceptual illustration of energy harvesting, leading to a perpetually powered sensor. This promises the possibility of sensors that use very small amounts of energy. What is needed is a method for downhole energy harvesting to power this new generation of electronics. The major sources of energy downhole are fluid flow, vibration, acoustics and heat. While the system described herein is based on the conversion of fluid flow using piezo electrics, conversion can also be accomplished using vibrating cantilevers, accelerometers, induction coils and magnets, impellers and other means. There must be fluid flow for the vortex energy harvester to work. Where no flow is present, vibration, acoustics or heat transfer can be utilized. In some cases all three can be utilized together.
The systems and methods described herein address these needs.